Websites figure predominantly in everyday life. However, many websites remain inaccessible to autistic people, and existing efforts to improve accessibility are in early stages, do not directly include autistic users in their development, or have not been empirically evaluated. The Academic Autism Spectrum Partnership in Research and Education (AASPIRE) used a community-based participatory research approach to create a website to improve health care access for autistic adults. We used the creation of that website as a “living laboratory” to develop the AASPIRE Web Accessibility Guidelines for Autistic Web Users. Our guidelines are grounded in accessibility theory, had autistic end-user involvement at all stages, and were empirically evaluat...